Evening primrose/Flor de la Oración (Oenothera mollisima)

Oenothera is a genus of about 125 species of annual, biennial and perennial herbaceous flowering plants, native to North and South America. It is the type genus of the family Onagraceae. Oenothera mollisima is an annual herb, around 100 cm high which grows in Uruguay, Brazil, Argentina, and most eastern South America. Its stems are rather woody, often branched, and softly hairy. The Leaves are basal or alternate, narrow-lanceolate to elliptic shaped, usually 3–5 cm long, 4–10 mm wide with an acute apex, regular margins and shallow teeth. Flowers usually bloom in February, March, April, May, November; opening in the evening and fading the next morning. They are solitary arranged in the upper leaf axils. They have four petals which are 10–20 mm long, yellow and often become reddish with age. One of the most distinctive features of this genus is the stigma with four branches, forming an “X” shape. Pollination is achieved by Lepidoptera (moths) and bees. Like many members of the Onagraceae, however, the pollen grains are loosely held together by viscin threads, meaning that only bees that are morphologically specialized to gather this pollen can effectively pollinate the flowers. Furthermore, the flowers are open at a time when most bee species are inactive, so the bees which visit Oenothera are also compelled to be vespertine temporal specialists. The plant eventually yields a dehiscent fruit, a capsule (cylindric, often curved, hairy), non-fleshy, 11–30 mm long, 3.5–6 mm wide with numerous seeds. In the wild, Oenothera mollisima acts as a primary colonizer, quickly appearing wherever a patch of bare, undisturbed ground may be found. This implies that it tends to be found in poorer environments such as dunes, roadsides, railway embankments and wasteland.